Knot pushing and positioning instruments are known in the art. U.S. Pat. No. 2,595,086 to LARZELERE, discloses a ring-shaped structure having an open slot. In use, a ligature is placed around an anatomical structure and both strands of the ligature are positioned on the periphery of a slotted ring structure. The knot itself is positioned in a slot formed in the ring and the slack strands are taken up together as the knot is pushed onto an anatomical structure. The ring structure is attached to a rod which is used to manipulate the tool and to push the knot into position.
FIG. 10 shows the working end of another prior art knotpushing device referred to as the Clarke-Reich ligator, which is distributed by Marlow Surgical Technologies, and which is intended for endoscopic use. This structure shows an aperture which communicates to the outside of the instrument through a slot. In use, one strand of the ligature is placed in the aperture by passing it through the slot. The tool is pushed causing the knot to slip over itself as it moves into position.
Open structures as taught by this prior art are difficult to use, since the instrument may slip off the ligature. Such structures can also have a tendency to become tangled with the knot and are not useful for untangling a knot. The seat of the Clarke-Riech ligator is particularly problematical when it engage an open loop of a loosely tied knot. The geometry of this device prevents knots from being effectively tightened. Also, the conventional use of the Clarke-Reich ligator on secondary knots frays the ligature which weakens it. Most surgeons do not prefer tools which form loose knots in frayed ligature. These problems have collectively spawned the development of the endoscopic surgical stapler.